1. Field of the Invention
The present invention relates to a method for treatment of cataract which comprises administering a radical scavenger such as a reducing thiol derivative, or a disulfide derivative or a sulfide derivative thereof.
2. Description of the Prior Art
In recent years, the incidense rate of senile cataract has been increasing with the increase in the rate of aged people in the population in Japan. Mechanisms of outbreak or progress of cataract have not been elucidated; however, it is now thought that pathogenic matter causes faculty in biological anti-oxidation system to generally grow weak and then lens proteins aggultinate to generate opacity in the lens. The faculty in biological anti-oxidation system seems to grow weak by the following mechanisms: (1) in the course of progress of cataract, generation of reaction system in which anti-oxidant in the lens is abnormally consumed; and (2) defluxion of glutatione (GSH) of reducing biocomponents by diffusion with other components in the lens due to abnormal transpenetration of membrane of the lens. Opacity of the lens is also suggested to be caused by change of ion balance of Na/K and irreversibility of ion balance by Ca.sup.2+.
Aldose reductase inhibitors (ARIs) have been developed as anti-cataract agents for diabetic cataract and some effective compounds have been proposed in animal experiments. However, one of potential ARIs killed 3 patients in its clinical trial in the United States, therefore, this kind of anti-cataract agent was stopped from being used. A possible anti-cataract agent has been expected to be developed for a long time.
The inventors have studied as anti-cataract agents some inhibitors of the lowering of faculty in biological anti-oxidation system and the present invention was made in the course of that study.